Researchers are trying to understand the impact of the Atlantic's big cycles.

If you look at a graph of global temperature over the last century, something probably jumps out at you: a dip around the 1960s. There have been several thoughts about this period of cooler temperatures. Some have pointed to fluctuating human aerosol (fine particle) emissions, which reflect sunlight and can cool the planet, as an important factor. Others have suggested that longer-term variation in Atlantic Ocean circulation—termed the Atlantic Multidecadal Oscillation, or AMO—was the driver. To complicate matters, aerosols may have influenced the AMO, or the two may have had a combined impact.

Surface water that flows into the North Atlantic cools as it nears the Arctic, sinks into the deeps, and flows back to the south, driving the conveyor belt of circulation in the Atlantic. It’s thought that the AMO involves a strengthening or weakening of that sinking over the span of a decade or more—causing the conveyor belt to slow down or speed up. Because the distribution of cold and warm water at the surface changes, the AMO can affect both regional and global climate (as does the El Niño Southern Oscillation, which tends to cycle on shorter time scales).

The Atlantic Multidecadal Oscillation has been a hot topic of research in recent years, but lots of questions remain. Because it’s so slow, there are only a couple oscillations in the instrumental temperature record. That’s not much to work with in terms of understanding what drives the AMO and how it impacts global climate. It has been studied in temperature proxy records of the last millennium, and even in ice cores, but its behavior appears to change with time. In some records, it looks like it oscillates over about 60 years, but in others it seems to only take 20 years. Similar behavior arises in some climate models, as well, but the specifics differ from model to model.

A new paper takes an interesting route to study the AMO further into the past by using the longest-running temperature record on the planet. Measurements have been taken in central England since 1659—shortly after sealed liquid thermometers were invented. Of course, it’s a local record and not the global average. But after comparing it to global temperatures going back to 1850, researchers Ka-Kit Tung and Jiansong Zhou of the University of Washington believed global patterns were reflected in the central England record well enough to justify the analysis.

They identified a dominant AMO-like oscillation 50 to 80 years in length throughout the record. Based on their analysis, they think the AMO had a role in all the largest climate shifts of the last 400 years. The Little Ice Age, a cool period in the 16th to 19th centuries, was likely caused by a lull in solar output and a string of large volcanic eruptions, but the researchers believe a downward swing of the AMO prolonged the cooling, and the subsequent upward swing helped bring it to an end.

They attribute a large portion of the warming in the first half of the 20th century to the AMO, with a secondary role for anthropogenic greenhouse gases and a small boost from solar activity. They also attribute the cooling around the 1960s and some of the warming in the 1990s to the AMO. In fact, after removing their calculated AMO contribution from the 20th century, they concluded that human-caused warming has been relatively linear since about 1910, at about 0.08°C per decade. That’s about half the rate estimated by others who have tried to account for sources of natural variability over the last 30 years (the span for which satellite data is available).

Tom Delworth, a researcher at NOAA’s Geophysical Fluid Dynamics Laboratory who has studied the AMO, told Ars that those calculations are a bit of a stretch. “I have serious reservations about the central conclusions of the paper,” Delworth said. “I think it tries to draw conclusions which are really beyond the scope of the evidence available.”

Delworth’s primary concern is the use of the central England temperature record as a global indicator. Because the AMO affects the distribution of temperatures, warming in the North Atlantic can be offset by a corresponding cooling in the South Atlantic. Teasing apart the precise extent to which the AMO influenced global temperature is a difficult task, and Delworth noted that the study’s “conclusions are very different than most of the work in the field.”

Another researcher told Ars that while the study is interesting, the AMO is still too poorly understood. Further research using climate models could help scientists work out the processes underlying the AMO that might cause its behavior to vary (which could include human alterations of climate). That could help us understand its role in the 20th century.

51 Reader Comments

"I think it tries to draw conclusions which are really beyond the scope of the evidence available.”

This is a pretty telling quote that applies to more than just one specific study in climate science. I don't profess to be a scientist or anything close to the sort, but it seems probable to me that the most likely answer to the heating and cooling of the earth is the most reasonable - that is that multiple variables contribute to the heating and cooling of the earth and single factors are not likely the sole catalyst for extreme change.

It's reasonable to conclude based on the amount and complexity of variables involved that both natural and human factors play a role - the problem, and the subject of controversy, is determining the proportion and ratio.

"A Climate seesaw in the Atlantic: Researchers are trying to understand the impact of the Atlantic's big cycles"

A Climate Seesaw in the Atlantic: The science is settled."

There, i fixed it for you.

Like NullValues, my ability to believe we are capable of modelling, let alone understanding or even knowing about all the variables is cemented - we do not.

Gordon Moore pointed out that by the late 90's, everyone realized that what Greenpeace stood for was good and reasonable. And once you get everyone agreeing with you, it becomes harder and harder to fight.

I don't know of anyone, even old, white, heterosexual, Christan males that believe poisoning the water and destroying the seas or deforesting the planet are good or okay ideas.

but when you try to pin all changes to an unknowable system to a single molecule, that is when you have turned off your brain and gone religious. And the level of religiosity of those who believe in the perfection of their models and the completeness of their vairables - it makes me believe you're not interested in science.

*of course* we don't understand the Atlantic cycles - because we have been around for not very long, have very little direct evidence from the past, most of which is one or two levels of corellation away from truth. Its ivory tower religion. Pure and simple.

Lets get back to science - where we go and test things that are provable and can be replicated, free from all dogma and religion. Can we?

In fact, after removing their calculated AMO contribution from the 20th century, they concluded that human-caused warming has been relatively linear since about 1910, at about 0.08°C per decade.

I have to strongly agree with Tom Delworth -- coming to a conclusion like that by using the central England temperature as a global temperature indicator should be so full of caveats the list of them should be longer than the paper itself.

Delworth noted that the study’s “conclusions are very different than most of the work in the field.”

Next they'll be recanting under pressure from the Church of Climatology.

What are the uncertainties reported in the paper's attributions to each source? They are using a much longer time series of a much less precise sensor, intuitively they should be well-positioned to detect cycles but have fairly wide confidence bands on their estimates.

"A Climate seesaw in the Atlantic: Researchers are trying to understand the impact of the Atlantic's big cycles"

A Climate Seesaw in the Atlantic: The science is settled."

There, i fixed it for you.

Like NullValues, my ability to believe we are capable of modelling, let alone understanding or even knowing about all the variables is cemented - we do not.

Gordon Moore pointed out that by the late 90's, everyone realized that what Greenpeace stood for was good and reasonable. And once you get everyone agreeing with you, it becomes harder and harder to fight.

I don't know of anyone, even old, white, heterosexual, Christan males that believe poisoning the water and destroying the seas or deforesting the planet are good or okay ideas.

but when you try to pin all changes to an unknowable system to a single molecule, that is when you have turned off your brain and gone religious. And the level of religiosity of those who believe in the perfection of their models and the completeness of their vairables - it makes me believe you're not interested in science.

No one is pinning all climate change on CO2 -- if someone is you should ignore them because they are incorrect.

In fact, after removing their calculated AMO contribution from the 20th century, they concluded that human-caused warming has been relatively linear since about 1910, at about 0.08°C per decade.

I have to strongly agree with Tom Delworth -- coming to a conclusion like that by using the central England temperature as a global temperature indicator should be so full of caveats the list of them should be longer than the paper itself.

To be fair, they do frame it with a little bit of "If this is correct, it would follow that..."

I have also noticed that a recent Norwegian study suggests we are over-estimating the amount of global warming. I personally still think we have not proerply taken into account the urban heat island effect. I know we have tried but the problem is China's data (or lack thereof) makes it very difficult. We should have a very good sense for how much of a warming problem we have in about two to three more years (because the urban heat island effect is no longer causing additional inflation in the data). Regardless, the USA really needs to work on increasing wind and solar energy production (but for solar, in ways that don't use water) so as to become more energy independent. In that regard, I want to see the government invest in the grid (and leave investment in companies that make products to the people that actually understand what it means to invest based on risk/reward). The government is good at doing utility-based projects. It sucks at making products or understanding markets.

"A Climate seesaw in the Atlantic: Researchers are trying to understand the impact of the Atlantic's big cycles"

A Climate Seesaw in the Atlantic: The science is settled."

There, i fixed it for you.

Like NullValues, my ability to believe we are capable of modelling, let alone understanding or even knowing about all the variables is cemented - we do not.

Gordon Moore pointed out that by the late 90's, everyone realized that what Greenpeace stood for was good and reasonable. And once you get everyone agreeing with you, it becomes harder and harder to fight.

I don't know of anyone, even old, white, heterosexual, Christan males that believe poisoning the water and destroying the seas or deforesting the planet are good or okay ideas.

but when you try to pin all changes to an unknowable system to a single molecule, that is when you have turned off your brain and gone religious. And the level of religiosity of those who believe in the perfection of their models and the completeness of their vairables - it makes me believe you're not interested in science.

*of course* we don't understand the Atlantic cycles - because we have been around for not very long, have very little direct evidence from the past, most of which is one or two levels of corellation away from truth. Its ivory tower religion. Pure and simple.

Lets get back to science - where we go and test things that are provable and can be replicated, free from all dogma and religion. Can we?

Many scientists have said this over and over again. Climate models are pretty worthless for making climate predictions. Are little more than video games. Sim Climate for researchers. None of them come even close to predicting short term trends we see today let alone the far future predictions many who push the Anthropogenic Global Warming view love to make. Our climate is extremely complex. We don't understand it anywhere nearly as well as AGW proponents would like us to believe. Science is pretty simple. You know you understand something when you can make accurate and reliable predictions. Something we have yet to do. Hell, our climate is an open and dynamic system. This means not only do conditions within our planet's atmosphere have an impact on our climate. Conditions in our solar system have an impact on our climate as well. something very few, if any, of the existing models take into account. We are still learning about the planet's climate system and learning something new all the time. Those who claim the science is settled are either incredibly ignorant or trying to push a political agenda. The high priest Al gore made it clear he doesn't buy the crap he's been pushing for years in his selling Current TV to a big oil producer. Oil money will now be funding Current TV. I find that deliciously ironic.

Both the authors and folks like Tom Delworth seem to have fallen into the same pit. I call it the "keys under the lamppost" problem after the allegorical man who dropped his keys in a dark alley then spent all his time looking under the distant but well-lit lamppost.

The authors are using what data they have to make their conclusion even while admitting that the data is far from sufficient. Delworth (and correct me if I'm misinterpreting) seems to be saying that while the AMO is certainly a large component of global climate, since we don't know how much, we'll assume it's zero.

In science/engineering terms, both in a fervor to gain precision have ignored accuracy.

Nice article and interesting analysis. There have already been a couple of papers, e.g., Klyashtorin and Lyubushin (2007), Loehle and Scafetta (2011), etc., which discuss the observational evidence for various ~60 yr cycles. As always I'm "skeptical" of drawing too firm a conclusion from a very limited (localized) data, but they are real data, so they shouldn't just be brushed aside either.

I want to point, however, that Scott seems to be repeating a conceptual mistake that he also made the last time he mentioned the THC in an article:

"Surface water that flows into the North Atlantic cools as it nears the Arctic, sinks into the deeps, and flows back to the south, driving the conveyor belt of circulation in the Atlantic. It’s thought that the AMO involves a strengthening or weakening of that sinking over the span of a decade or more—causing the conveyor belt to slow down or speed up."

We don't understand the entire cause-and-effect relationship, but the convective mode is likely not the main driver of the large-scale circulation. (This is discussed in the references for the "Thermohaline circulation" Wikipedia entry linked in the article.) Hence, the AMO seems at least as likely to be a feedback as a driver of the variation discussed in the PNAS article.

I'm 100% fine with spending large amounts of money funding more research like this and in general regarding the climate and climate change.

I'm just not comfortable funding "solutions" at this point.

We should always be striving to learn as much as we can about all of our planet's systems. That knowledge can only help humanity's continued survival as well as prepare us for the day when we are seeking a habitable world to colonize. It will help us better know what to look for.

I'd love to know how we can fund a solution to a problem we don't understand? We don't even know if there is a problem to be solved.

I am just about as skeptical of this result as I am of climate models that attribute a much larger fraction of the observed warming to anthropogenic causes.

I will say that the fact that we know very little about natural climate variablity, and the fact that our models appear to replicate the observed oscillations poorly at best, certainly calls for less certainty on the part of those who are running the climate models, and further study into natural climate variability.

"I personally still think we have not proerply taken into account the urban heat island effect."

Heh. I've been beating that drum here a while, but they've got some pretty decent data that says it isn't so, all I've got are my anecdotal observations that says it is. Hope you're prepared to be beat about the face and neck with a whole lotta science.

Anyway, we've got this news, in the same week that the government of Norway says we've been overestimating the warming. (Odd that I haven't seen an article on that yet.) And these comments are (so far) running more skeptic than advocate.

I'm 100% fine with spending large amounts of money funding more research like this and in general regarding the climate and climate change.

I'm just not comfortable funding "solutions" at this point.

We should always be striving to learn as much as we can about all of our planet's systems. That knowledge can only help humanity's continued survival as well as prepare us for the day when we are seeking a habitable world to colonize. It will help us better know what to look for.

I'd love to know how we can fund a solution to a problem we don't understand? We don't even know if there is a problem to be solved.

And there lies the problem I have with the bulk of the global warming campaign. If the warming is abnormal, fine. If we're a small/medium/large part of the problem, fine. But lets better understand the problem before we start spending billions on "solutions" that may or may not solve a problem that we may or may not have, and may or may not be able to solve.

Many scientists have said this over and over again. Climate models are pretty worthless for making climate predictions. Are little more than video games. Sim Climate for researchers. None of them come even close to predicting short term trends we see today let alone the far future predictions many who push the Anthropogenic Global Warming view love to make. Our climate is extremely complex. We don't understand it anywhere nearly as well as AGW proponents would like us to believe. Science is pretty simple. You know you understand something when you can make accurate and reliable predictions. Something we have yet to do. Hell, our climate is an open and dynamic system. This means not only do conditions within our planet's atmosphere have an impact on our climate. Conditions in our solar system have an impact on our climate as well. something very few, if any, of the existing models take into account. We are still learning about the planet's climate system and learning something new all the time. Those who claim the science is settled are either incredibly ignorant or trying to push a political agenda. The high priest Al gore made it clear he doesn't buy the crap he's been pushing for years in his selling Current TV to a big oil producer. Oil money will now be funding Current TV. I find that deliciously ironic.

Nice article and interesting analysis. There have already been a couple of papers, e.g., Klyashtorin and Lyubushin (2007), Loehle and Scafetta (2011), etc., which discuss the observational evidence for various ~60 yr cycles. As always I'm "skeptical" of drawing too firm a conclusion from a very limited (localized) data, but they are real data, so they shouldn't just be brushed aside either.

I want to point, however, that Scott seems to be repeating a conceptual mistake that he also made the last time he mentioned the THC in an article:

"Surface water that flows into the North Atlantic cools as it nears the Arctic, sinks into the deeps, and flows back to the south, driving the conveyor belt of circulation in the Atlantic. It’s thought that the AMO involves a strengthening or weakening of that sinking over the span of a decade or more—causing the conveyor belt to slow down or speed up."

We don't understand the entire cause-and-effect relationship, but the convective mode is likely not the main driver of the large-scale circulation. (This is discussed in the references for the "Thermohaline circulation" Wikipedia entry linked in the article.) Hence, the AMO seems at least as likely to be a feedback as a driver of the variation discussed in the PNAS article.

I actually expected you to bring this up when I wrote that simplification. If you think there's a better way to simply describe the THC, I'm all for hearing it. (Tone: no snark) Do you mainly think I shouldn't be leaving out the surface wind component?

"I think it tries to draw conclusions which are really beyond the scope of the evidence available.”

This is a pretty telling quote that applies to more than just one specific study in climate science.

Condemning research without even telling us what it was...

NullValues wrote:

It's reasonable to conclude based on the amount and complexity of variables involved that both natural and human factors play a role - the problem, and the subject of controversy, is determining the proportion and ratio.

my ability to believe we are capable of modelling, let alone understanding or even knowing about all the variables is cemented - we do not.

Some of them are understood quite well. This AMO business just happens to be difficult because of that "M" (multidecadal): the cycle, if there is one, seems to be too long for anyone to have good data on it. Yet.

Next they'll be recanting under pressure from the Church of Climatology.

More garbage...

FrankM wrote:

What are the uncertainties reported in the paper's attributions to each source?

Followed by an actual legit question! Woo. Nice to see an exception. I'll see if I can access the paper in a minute.

Steve Sheldon wrote:

I personally still think we have not proerply taken into account the urban heat island effect.

Dumb and very much outdated...

g0m3r619 wrote:

Climate models are pretty worthless for making climate predictions. Are little more than video games. Sim Climate for researchers. None of them come even close to predicting short term trends we see today let alone the far future predictions many who push the Anthropogenic Global Warming view love to make.

Conditions in our solar system have an impact on our climate as well. something very few, if any, of the existing models take into account.

Besides the sun (which, yes, is in the models), what exactly do you mean? Neptune doesn't really affect our climate.

g0m3r619 wrote:

The high priest Al gore made it clear he doesn't buy the crap he's been pushing for years in his selling Current TV to a big oil producer. Oil money will now be funding Current TV. I find that deliciously ironic.

More off-topic garbage.

John Is My Name wrote:

If the warming is abnormal, fine. If we're a small/medium/large part of the problem, fine. But lets better understand the problem before we start spending billions on "solutions" that may or may not solve a problem that we may or may not have, and may or may not be able to solve.

Nice article and interesting analysis. There have already been a couple of papers, e.g., Klyashtorin and Lyubushin (2007), Loehle and Scafetta (2011), etc., which discuss the observational evidence for various ~60 yr cycles. As always I'm "skeptical" of drawing too firm a conclusion from a very limited (localized) data, but they are real data, so they shouldn't just be brushed aside either.

I want to point, however, that Scott seems to be repeating a conceptual mistake that he also made the last time he mentioned the THC in an article:

"Surface water that flows into the North Atlantic cools as it nears the Arctic, sinks into the deeps, and flows back to the south, driving the conveyor belt of circulation in the Atlantic. It’s thought that the AMO involves a strengthening or weakening of that sinking over the span of a decade or more—causing the conveyor belt to slow down or speed up."

We don't understand the entire cause-and-effect relationship, but the convective mode is likely not the main driver of the large-scale circulation. (This is discussed in the references for the "Thermohaline circulation" Wikipedia entry linked in the article.) Hence, the AMO seems at least as likely to be a feedback as a driver of the variation discussed in the PNAS article.

I actually expected you to bring this up when I wrote that simplification. If you think there's a better way to simply describe the THC, I'm all for hearing it. (Tone: no snark) Do you mainly think I shouldn't be leaving out the surface wind component?

I think you do a decent job of balancing the need to be precise against the need to be concise. Your articles are pretty accessible. No, I don't think you should have brought all the possible drivers of the AMO into it; your article might have run long and lost a lot of readers.

If we were going to nit-pick, maybe "driving" could be replaced with "one of the main drivers.." or "assumed", or something like that. But I wouldn't want to read through qualifiers on everything, and end up missing the point you were trying to make.

Many scientists have said this over and over again. Climate models are pretty worthless for making climate predictions. Are little more than video games. Sim Climate for researchers. None of them come even close to predicting short term trends we see today let alone the far future predictions many who push the Anthropogenic Global Warming view love to make. Our climate is extremely complex. We don't understand it anywhere nearly as well as AGW proponents would like us to believe. Science is pretty simple. You know you understand something when you can make accurate and reliable predictions. Something we have yet to do. Hell, our climate is an open and dynamic system. This means not only do conditions within our planet's atmosphere have an impact on our climate. Conditions in our solar system have an impact on our climate as well. something very few, if any, of the existing models take into account. We are still learning about the planet's climate system and learning something new all the time. Those who claim the science is settled are either incredibly ignorant or trying to push a political agenda. The high priest Al gore made it clear he doesn't buy the crap he's been pushing for years in his selling Current TV to a big oil producer. Oil money will now be funding Current TV. I find that deliciously ironic.

"Science is pretty simple." Really? Science is simple? That must be why all those business majors switch into Electrical Engineering for the easy A. /sarcasm

Yes science is simple. Something tells me you have no idea how it works. You study something until you feel you understand it. The test of whether or not you understand it is prediction. Based on what you think you know about something you should be able to make accurate predictions multiple times. if you can't do this then it tells you that you clearly do not understand the thing you were studying and need to study it some more. That's pretty simple. Simple enough even for someone like you. Fact is none of the AGW camp have been able to make reliable and accurate predictions. you may also like to look into the work of Piers Corbyn. He's come up with a system to make fairly accurate predictions of climate conditions over the short term. He's been so accurate that many farmers use his data in their planning. He uses data based on the moon and the sun and is far more accurate than anyone else has been. This should tell anyone with a brain that he has a better understanding of our climate than the people you seem to look to.

If the warming is abnormal, fine. If we're a small/medium/large part of the problem, fine. But lets better understand the problem before we start spending billions on "solutions" that may or may not solve a problem that we may or may not have, and may or may not be able to solve.

...and some classic, ignorant FUD. Great.

How is it ignorant? Do you think we *FULLY* understand the problem? Do you think we haven't wasted time/money/resources on "solutions" that have done nothing, or "solutions" that actually caused more harm? Do you think that much of the waste wasn't knee-jerk reactions to a problem that is still being studied?

If the warming is abnormal, fine. If we're a small/medium/large part of the problem, fine. But lets better understand the problem before we start spending billions on "solutions" that may or may not solve a problem that we may or may not have, and may or may not be able to solve.

...and some classic, ignorant FUD. Great.

How is it ignorant? Do you think we *FULLY* understand the problem? Do you think we haven't wasted time/money/resources on "solutions" that have done nothing, or "solutions" that actually caused more harm? Do you think that much of the waste wasn't knee-jerk reactions to a problem that is still being studied?

I just read the article and nothing here suggests that they "believe poisoning the water and destroying the seas or deforesting the planet are good or okay ideas".

Here's a few clips pertaining to their objections (to the act, not clean water per se).

-- Association spokesperson Peter Archer described Bill 43, the Clean Water Act as a -- draconian piece of legislation that will impose severe hardship of farmers across the province.

-- They (the government) cant keep putting land restrictions on us without any compensation, said Archer.

-- With this act the government will have the right to forceable entry on our properties if they -- believe there is a problem…thats not a free and just society.

-- During the brief exchange with the premier, Archer said the legislation would place a severe-- hardship on farmers. What good will it do? he asked.

There don't seem to be a lot of specifics. This is dated from 2006, potentially it should be possible to see what legislation was passed and what the outcome was, but I don't have the time for that now.

EDIT:

I can't find anything further on the ontario issue other than the Act seems to have passed.

But it's interesting that legislation of a similar nature is being protested in the US.

-- Routine maintenance work like shoveling dirt into a water-filled ditch that flows into a stream-- could soon become a costly violation without a acquiring a federal permit.

-- If proposed change to the Clean Water Act is approved, the Environmental Protection Agency-- would have the authority to protect from pollution almost any wet area on private land. The -- controversial change, which has been lambasted by government leaders and farm groups, -- would allow the federal agency to regulate all “waters of the U.S” by removing the phrase-- “navigable waters” from the law.

-- Established in 1972, the CWA now allows the government to regulate the discharge of any-- pollutant — including sand or dirt — that have “significant nexus” to “navigable waters.” The-- definition of navigable waters includes all interstate waters, along with intrastate lakes, -- rivers and streams used by interstate travelers for recreation or other purposes.

...

-- “There’s no approval or public hearing process” to pass this, Mr. Ammerman said. “We -- don’t believe it’s proper authority. People would face civil and criminal penalties by just-- doing routine maintenance in a ditch to fight soil erosion. You may have to get a general-- federal use permit to get anything changed, and those can take up to a year to approve-- and cost anywhere from $35,000 to $100,000.”

And geez, downvoted for reading an article to see if it said what it was purported to say? Only at ars.The truth may set you free, but here you'll get downvoted for it.

Interesting. Sounds like their assumptions leave a lot of room for error, but at least they explain their assumptions and justify their use. It sounds like an area that isn't well understood since it's not something we have a lot of solid data to extrapolate from. That means that it's reasonable to be skeptical about the details of their projections. However, I also wonder that since we don't understand AMO well could it be having a larger effect than we suspect. Climate appears to be effected by such a broad set of effects, and we don't have nearly enough historical data to understand them all very well.

Of course it's not like we can just wait a couple thousand years to gather more data before making our best guesses.

This research seems like a good effort at trying to understand AMO. It may not have a lot of value by itself, but they can continue to look for other data that collaborates their theories and it gives other researchers another possible theory to consider.

Interesting. Sounds like their assumptions leave a lot of room for error, but at least they explain their assumptions and justify their use. It sounds like an area that isn't well understood since it's not something we have a lot of solid data to extrapolate from. That means that it's reasonable to be skeptical about the details of their projections. However, I also wonder that since we don't understand AMO well could it be having a larger effect than we suspect. Climate appears to be effected by such a broad set of effects, and we don't have nearly enough historical data to understand them all very well.

Of course it's not like we can just wait a couple thousand years to gather more data before making our best guesses.

This research seems like a good effort at trying to understand AMO. It may not have a lot of value by itself, but they can continue to look for other data that collaborates their theories and it gives other researchers another possible theory to consider.

I think from the way this paper calculates it, it wouldn't be unfair to say they give the maximum possible contribution from the AMO.

I love reading about new research, and I think we should keep doing everything we can to learn about how all these things (AMO, El Nino, solar cycles, etc.) work together. Someday perhaps our models will be detailed and powerful enough to predict what conditions will be like more than a few weeks into the future.

However, I don't think it matters except as a way to help us prepare. The climate is not a steady state system. It has been constantly changing for billions of years, and it will continue to change far into the future, whether we want it to or not, and in spite of what we might try to do to stop it. Some of us will need more sunscreen, some will need to buy a heavier coat, and we will just have to live with it.

What are the uncertainties reported in the paper's attributions to each source?

[Followup] Turns out that's not a simple thing to answer, since the paper seems to be largely about statistical analysis of multiple sources, and removing the factors which are not part of the AMO. So unfortunately I can't just give you a numerical range.

As an example, here's Figure 3 from the paper. I can send the whole PDF if you're interested enough.

If the warming is abnormal, fine. If we're a small/medium/large part of the problem, fine. But lets better understand the problem before we start spending billions on "solutions" that may or may not solve a problem that we may or may not have, and may or may not be able to solve.

No. But that's because this is science, where 100% understanding of any one problem generally requires solving much more challenging underlying questions about the universe. Plus there can be mathematical limits to what we can know or compute; even the best supercomputer couldn't model our entire atmosphere down to the atom.

Quote:

Do you think we haven't wasted time/money/resources on "solutions" that have done nothing, or "solutions" that actually caused more harm? Do you think that much of the waste wasn't knee-jerk reactions to a problem that is still being studied?

Those are vague and leading questions. Hence why I referred to your previous comment as "FUD". I'll gladly retract that if you give us some specific examples, instead of these "gotcha" generalizations.

I personally still think we have not proerply taken into account the urban heat island effect.

Dumb and very much outdated...

I guess you never read the studies and took time to understand the underlying data. If you had, you would have realized the papers are inconclusive. Berkeley Earth, for example, is based on a global review but the problem is filter is too impercise to actually provide meaningful data. Indeed, they admit as much in the paper. Of course a bunch of anaylsis is done but if your data is crap, the results are not going to be any better. In addition, we don't have quality records for most of the world where there was a significant change from rural to urban. I accept that you don't want to consider this point any further and I admit it is pretty much impossible to get good data (other than the US - which is not really large enough to provide a definitive answer) but your suggestion that this issue is decided is typical of someone that really doesn't understand what they are talking about and instead has decided something is true. The bottom line is that I don't believe the data is good enough to support only one conclusion. Ad hominem seem to be an MO for you so I will respectfully chose to ignore you (please feel free to do the same for me).

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I personally still think we have not proerply taken into account the urban heat island effect.

Dumb and very much outdated...

I guess you never read the studies and took time to understand the underlying data. If you had, you would have realized the papers are inconclusive. Berkeley Earth, for example, is based on a global review but the problem is filter is too impercise to actually provide meaningful data. Indeed, they admit as much in the paper. Of course a bunch of anaylsis is done but if your data is crap, the results are not going to be any better. In addition, we don't have quality records for most of the world where there was a significant change from rural to urban. I accept that you don't want to consider this point any further and I admit it is pretty much impossible to get good data (other than the US - which is not really large enough to provide a definitive answer) but your suggestion that this issue is decided is typical of someone that really doesn't understand what they are talking about and instead has decided something is true. The bottom line is that I don't believe the data is good enough to support only one conclusion. Ad hominem seem to be an MO for you so I will respectfully chose to ignore you (please feel free to do the same for me).

Technically it is not a logical fallacy if the argument is dumb and outdated. Whereas deciding research results you don't like are crap because you don't like the results or implications is a logical fallacy. Perhaps you might want to learn about the urban heat island effect before commenting on it.

What are the uncertainties reported in the paper's attributions to each source?

[Followup] Turns out that's not a simple thing to answer, since the paper seems to be largely about statistical analysis of multiple sources, and removing the factors which are not part of the AMO. So unfortunately I can't just give you a numerical range.

As an example, here's Figure 3 from the paper. I can send the whole PDF if you're interested enough.

Spoiler: show

I understand that it's not exactly 1.96 times the standard deviation, but if they are going to state something like 0.08C per decade, there should be some reported range. Or they could go all Bayesian on us and report a credible interval with a plot of the posterior distribution.

These are very different results:0.08C/decade +/- 0.02C0.08C/decade +/- 0.13C0.08C/decade (0.05 - 0.17)

There recent article on proton diameter measurements being 7 sigma apart sheds light on this problem.